Chitin (N-acetyl glucosamine) is a naturally occurring polysaccharide and many of its derivatives, including chitosan, have applications in the biomedical field. Chitosan is a deacetylated chitin derivative and includes a variety of polymers with different degrees of deacetylation and depolymerization. Most chitosans are soluble at pHs below 7 and many form hydrogels when dissolved in aqueous solutions.
Over the last decade, chitin and its derivatives have become the focus of interest in biomedical and biopharmaceutical research. As a biocompatible polymer, chitosan has been used for a variety of applications as a biomaterial for tissue engineering, wound healing, and as an excipient for drug delivery. Chitosan can be used as a drug delivery agent for a wide variety of therapeutics. For example, DNA complexation with chitosan yields suitable nano- and micro-particulate formulations for transfection in vivo and in vitro. In addition, peptide and protein delivery using chitosan as functional carriers has also been reported.
However, at neutral and basic pHs, underivatized chitosan aggregates and precipitates out of solution. This has limited the applications of underivatized chitosans in oral drug delivery, due to the neutral to alkaline environment of the intestinal tract.
Accordingly, it is an object of the invention to provide a method for delivering a therapeutic agent across a membrane that has limited permeability for the therapeutic agent. The therapeutic agent is provided to the membrane in a composition that includes a sulphated chitinous polymer.
It is also an object of the invention to provide a method for treating a subject with a therapeutic agent by administering the therapeutic agent to the subject in a composition having a sulphated chitinous polymer as a primary carrier.
These and other objects, features, and advantages of the invention will be apparent from the following description and claims.